Carbonization of crop straws plays an important role in the general utilization of straws. Methods and Devices for carbonization of crop straws become much well developed during the technology development, but some drawbacks still exist.
For example, as described in the Chinese Patent No. ZL200510044136.3, entitled “Carbonization Process for Vegetation With High Temperature and Floating Oxygen,” which requires two furnace bodies, i.e., inner furnace body and outer furnace body, wherein the entrance of the furnace chamber is open, and when the carbonization process begins, the vegetation is fed to the inner furnace through the entrance of the furnace chamber and fired to rapidly decompose, with combustible gases of high temperature exhausted to rise and fully contact with the floating oxygen in the air to form flames, and then the entrance of the furnace chamber is closed, and the vegetation continues to feed to keep the carbonization process in force, until the carbonization process is finished and thus the temperature is quickly lowered to below the firing point. However, the above vegetation carbonization process has the following disadvantages. Because the flame of vegetation thrown into the inner furnace seals the entrance of the furnace chamber of the inner furnace and thus the air cannot enter the lower portion of the inner furnace, the vegetation subsequently fed cannot be easily and completely carbonized. After the carbonization process is finished, it is complicated to discharge the charcoal from the inner furnace, and auxiliary time for discharging, etc., is longer in comparison with the time for pyrolysis carbonization. And the labor intensity of workers is heavy, and discharge cannot be performed until all the vegetation thrown into the inner furnace is carbonized and the temperature is reduced for a long time. After a previous discharge, operations to fill, carbonize and discharge is once again taken, resulting in time consuming and lower production rate. Furthermore, since the equipment takes a form of stationary structure, the cost for transporting crop straws is extremely high, and thus requirements of high efficiency, low cost and production in large scale cannot be fulfilled.
It is described in the Chinese Patent No. ZL01132888.6, entitled “A Device for Carbonization of by-Products of Crop Straws, Etc.” The device comprises a bottom opening provided in the bottom of a cylindrical container with a top cover, and a heat flux tube passing vertically through the bottom opening. An upper end of the heat flux tube terminates at a distance of 10 cm to the top of the cylindrical container, and the lower end thereof projects 3 cm downwards from the bottom of the cylindrical container to form a horizontal opening at the side of the cylindrical container. A gas tube communicating with the horizontal opening is provided on the cylindrical container and projects outwardly. A skirt-shaped base is provided at the lower end to support the whole cylindrical container, with a portion thereof opened as combustion opening. Heat insulation layers are provided at the sides and the top of the cylindrical container, and on the cover. After the fire is distinguished, carbonization products carbonized by the carbonization device is stored for 24 hours and then taken out after removing the cover. Thereafter, a next carbonization process is started. These limit the production rate of the carbonization of crop straws. Since the carbonization device takes a form of a stationary structure, the cost for transporting by-products of crop straws is extremely high, and the requirements of high efficiency, low cost and production in large scale cannot be fulfilled.
If a traditional kiln is used to carbonize crop straws, the production rate is high. However, the production cycle is quite long from several days up to tens of days, the efficiency and the safety are low, and the economical profit is not good. Solutions to problems of discharging the floating particles and poor environmental performance caused by the collection of wood tar and straw vinegar solution cannot be found, and thus it is not worth promoting.